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abstract: Reactive inkjet printing (RIJP) is a direct-write deposition technique that synthesizes and patterns functional materials simultaneously. It is a route to cheap fabrication of highly conductive features on a versatile range of substrates. Silver reactive inks have become a staple of conductive inkjet printing for application in printed and flexible electronics, photovoltaic metallization, and more. However, the high cost of silver makes these less effective for disposable and low-cost applications. This work aimed to develop a particle-free formulation for a nickel reactive ink capable of metallizing highly pure nickel at temperatures under 100 °C to facilitate printing on substrates like paper or plastic. Nickel offers a significantly cheaper alternative to silver at slightly reduced bulk conductivity. To meet these aims, three archetypes of inks were formulated. First were a set of glycerol-based inks temperature ink containing nickel acetate, hydrazine, and ammonia in a mixture of water and glycerol. This ink reduced between 115 – 200 °C to produce slightly oxidized deposits of nickel with carbon content around 10 wt %. The high temperature was addressed in a second series, which replaced glycerol with lower boiling glycols and added sodium hydroxide as a strong base to enhance thermodynamics and kinetics of reduction. These inks reduced between 60 and 100 °C but sodium salts contaminated the final deposits. In a third set of inks, sodium hydroxide was replaced with tetramethylammonium hydroxide (TMAH), a strong organic base, to address contamination. These inks also reduced between 60 and 100 °C. Pipetting or printing onto gold coated substrates produce metallic flakes coated in a clear, thick residue. EDS measured carbon and oxygen content up to 70 wt % of deposits. The residue was hypothesized to be a non-volatile byproduct of TMAH and acetate. Recommendations are provided to address the residue. Ultimately the formulated reactive inks did not meet design targets. However, this thesis sets the framework to design an optimal nickel reactive ink in future work. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2019

This thesis presents a comparative study between two silver nanoparticle inks that were deposited using a Drop-on-Demand (DoD) inkjet printer, aiming at finding a functional ink that can be used to print electrodes in Light-emitting Electrochemical Cells (LECs). To achieve this, a DoD inkjet printer was installed and an acquaintance with the printer was attained. Among the two inks, one was employed as received while the other was reformulated, and successful deposition of both the inks was observed. During the reformulation process, it was seen that the highly volatile tetrahydrofuran (THF) solvent can be used to improve the ink properties, in contrast to what is recommended. After that, the inks were deposited on UV-ozone treated glass substrates, sintered at an elevated temperature under ambient conditions, and their specific resistances and thicknesses were measured. Finally, the inks were used to print the anode in a structured sandwich-cell LEC. The performance comparison was conducted by observing the emitted light of the LECs. The results indicate that the reformulated ink performs better, probably due to the lower silver concentration that results in flatter surface, which in turn effectively alleviates shorts.

Made available in DSpace on 2014-10-09T12:26:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:32Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:05/58301-0

Made available in DSpace on 2014-10-09T12:26:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:32Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A análise de tintas e papéis é de grande interesse para a ciência e a interação tinta-papel é importante em vários níveis. A análise da tinta de um documento é extremamente importante para o estudo de diferentes aspectos, como adulterações e determinação da recentidade. Esses aspectos podem ser estudados analisando a tinta e o papel tanto fisicamente quanto quimicamente. Portanto, o desenvolvimento de uma técnica para a análise de tintas de caneta esferográfica e a determinação da recentidade de um documento é interessante para a Ciência Forense. No Brasil, cientistas forenses enfrentam todos os dias diversos casos que requerem a análise de tintas de caneta esferográfica, e não se tem nenhuma técnica onde a determinação da idade de uma tinta é possível. Os casos mais comuns onde há a necessidade da recentidade de um documento são fraudes em recibos de pagamento e de quitação de dívidas, preenchimento e assinatura de contratos, adulteração em documentos e em cheques. Neste trabalho, é discutida uma nova metodologia para a análise de tintas de canetas esferográficas e a sua utilização na determinação da recentidade de uma amostra de tinta de caneta esferográfica. Foram analisadas periodicamente amostras provenientes de diferentes países, como Estados Unidos, Canadá, Peru, Japão, Espanha e Grécia. Com os resultados obtidos, foram construídas curvas de degradação do solvente em função do tempo de preparo. Com as curvas, obtiveram-se as equações logarítmicas relativas. As equações propostas mostraram ser capazes de distinguir a idade relativa de uma tinta, com 20% de variação em relação ao valor teórico. Portanto, a principal conclusão deste trabalho é a metodologia proposta pode ser utilizada para determinar a idade relativa de uma tinta de caneta esferográfica. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:05/58301-0

Abstract In gravure offset printing, ink is transferred with the help of an offset material from a patterned gravure plate to a substrate. This thesis is concerned with the study and further development of this printing process for electronics; on alumina, glass and polymers. The work has been divided into five parts. In the first section, the printing process is described. The second section describes the composition of the inks for gravure offset printing and the resulting ink properties. It also presents the ink transfer mechanism; the model that explains how the ink is transferred between an offset material and a substrate. The third chapter details the printing process explained by a solvent absorption mechanism. The forth chapter describes the firing/curing of printed samples and their properties. The last chapter describes applications of the method. The inks used to produce conductors on ceramics (ceramic inks) and conductors on polymers (polymer inks) contain silver particles, and were under development for gravure offset printing. The major achieved properties were the high ink pickup to the offset blanket and high transfer percentage to the substrate. 100% ink transfer from blanket to substrate for ceramic inks and almost 100% ink transfer for polymer inks was obtained. The printing of ceramic inks was able to produce 8 μm of relatively thick, 300 μm wide lines with < 10 mΩ/sq. resistance. The minimum line width for conducting lines was 35 μm, with one printing. Multi printing was applied producing as many as 10 times wet-on-wet multiprinted lines with 100 % ink transfer from blanket to substrate resulting in a square resistance of 1mΩ/sq. Polymer inks were able produce a square resistance of 20 mΩ/sq. for 300 μm wide lines after curing at 140 °C for about 15 min, and the minimum width was down to 70 μm. In the optimised manufacturing process, the delay time on the blanket was reduced to 3 s. In addition to ultra-fine-line manufacturing of conductors, the method enables the manufacture of special structures e.g. laser-solder contact pads with 28/28 μm lines/spaces resolution. With industrial printing equipment it is possible to produce 100 m2/h with the demonstrated printing properties.

As a consequence of the widespread use of computers coupled to high-quality printers and different types of papers, forgery, counterfeiting, change of wills, anonymous letter writing and felonious use of the documents have become serious problems. Forensic analysts are always seeking methods that can provide reliable information on whether a specimen collected at the crime scene is linked to the crime or to a source of known origin. Sensitive methods that can provide more detailed characterization of natural or man-made materials or even provide information not previously available to forensic examiners. Recent advances in rapid solid sampling of materials using laser ablation (LA) coupled to inductively coupled plasma mass spectroscopy (ICP-MS) have led to this analytical method to be regarded as the “gold standard” in the field of elemental analysis for trace level components in solids. Another, emerging, analytical technique that uses the same laser pulse to generate a plasma that can be interrogated with spectroscopy is laser induced break down spectroscopy (LIBS). The analysis of ink and paper is also possible because of the surface removal effect of laser interactions with the samples. In the present study, printing inks were analyzed using LIBS, LA-ICP-MS and both of them in tandem mode. In the tandem setup, the light generated during the relaxation of the excited species (LIBS) was used to create a spectral signature of the elements, and the mass-to-charge ratio of the ejected particles (ICP-MS) was used to create a mass spectrum. For a set of 319 printing ink samples, LA-ICP-MS alone provided discrimination greater than 99%. A subset of 43 printing inks, having a very similar elemental profile, was analyzed by tandem LIBS/LA-ICP-MS. The fusion of LIBS and LA-ICP-MS provided additional discrimination through the detection of elements like Ca, Si, Fe, and K by LIBS, that are difficult to detect and confirm using standalone ICP-MS because of the spectral interferences (isobaric and polyatomic) involved. The combination of these two sensors was found to minimize the individual limitations and provide a more complete and representative chemical characterization of printing inks.

Baigiamajame magistro darbe atliktas įprastų ir UV dažų palyginamasis kokybės tyrimas. Atliktas įprastų ir UV dažų atspaudų spalvinių charakterisikų palyginimas esant D50 ir D65 šviesos šaltiniams, ištirtas spalvų spausdinimo stabilumas. Nustatyta, kad įprastųjų ir UV dažų galimų spalvų diapazonas yra artimas esant D50 šviesos šaltiniui ir akivaizdžiai skiriasi esant D65 šviesos šaltiniui, kas rodo skirtingą fluorescencinio komponento indėlį. Eksperimentiškai ištirtos popieriaus ofsetinių atspaudų trinties savybės ir nustatyti statinis ir kinetinis trinties koeficientai. Nustatyta, kad įprastiniai ir UV dažai didina atspaudo į popierių statitinio trinties koeficiento dydį ir mažina kinetinio koeficiento dydį. Atliktas dviejų rūšių popieriaus su įprastais ir UV dažais šiurkštumo palyginamasis tyrimas ir nustatyta, kad įprasti dažai atspaudų paviršiaus šiukštumą stipriai didina, o UV dažų poveikis priklauso nuo popieriaus rūšies. Išnagrinėjus teorinius ir praktinius įprastų ir UV dažų skirtumus, pateikiamos baigiamojo darbo išvados ir siūlymai. Darbą sudaro 6 dalys: įvadas, apžvalga, eksperimentinė dalis, rezultatai ir jų aptarimas, išvados ir siūlymai, literatūros sąrašas. Darbo apimtis – 67 p. teksto be priedų, 59 iliustr., 1 lent., 15 bibliografinių šaltinių. Atskirai pridedami darbo priedai. / In master of science thesis is investigated the quality of conventional and UV curable prints. Performed comparison between two types of inks color characteristics at illuminants D50 and D65 and examined colors printing stability. It was fund, that diapason of conventional and UV inks are more similar at illuminant D50 and it is significantly different at illuminant D65. Results mean, that fluorescence’s component is different in different type of inks. Experimentally investigated offset print’s friction properties and determined the static and kinetic coefficients of friction. Determined, that conventional and UV inks increase static friction coefficient and reduce kinetic friction coefficient between paper and print. Also, investigated two different types of paper and prints made with conventional and UV inks roughness properties comparison and determined, that conventional inks strongly increase roughness of prints surface and influence of UV inks depend on paper’s type. Structure: introduction, review, experiment, conclusions and suggestions, references. Thesis consists of: 67 p. text without appendixes, 59 pictures, 1 table, 15 bibliographical entries. Appendixes included.

Le potentiel des procédés d’impression dans les applications électroniques sur des supports en céramique a été démontré dans ce travail. Plusieurs techniques d’impression ont été étudiées : sérigraphie, flexographie, héliogravure et jet d’encre. Les propriétés de surface de plusieurs types de céramique ont été caractérisées avant et après frittage : taille des pores, rugosité et énergie de surface. Ces analyses ont permis de sélectionner les matières premières des encres les mieux adaptées à ces supports, ainsi qu’aux procédés d’impression considérés. Des formulations aqueuses à base de particules d’argent ont été privilégiées. Les propriétés de ces encres, rhéologie et tension de surface, ont été analysées et leurs effets sur la qualité des lignes imprimées (largeur, épaisseur et rugosité) ont été évalués. Après impression, les motifs ont été frittés. Des résistivités proches de celle de l’argent ont été obtenues (2 à 12x10-8 Ohm.m). L’originalité de ce travail réside notamment dans l’utilisation d’encres sérigraphiques à base d’eau et l’impression d’encres flexographiques sur des supports en céramique. Cette étude ouvre donc des perspectives pour l’industrialisation et la production de masse de composants électroniques sur supports céramiques souples. / This work demonstrates the printing processes potential for manufacturing ceramic based electronic devices. Several printing techniques were studied: screen printing, flexography, rotogravure and inkjet. Ceramic tapes surface properties were characterised: surface pore size, roughness and surface energy. These analyses allowed the selection of the inks raw materials adapted to the substrates and the printing processes. Water-based silver inks were formulated. Inks properties, rheology and surface tension, were analysed and their effect on line properties was investigated. Printed substrates were afterwards sintered. Resistivity values close to that of bulk silver were reached (2 to 12x10-8 Ohm.m). These work novelties are mainly the formulation of water-based environmentally friendly screen printing pastes and the flexography printing of silver inks onto ceramic substrates. This study offers new perspectives for the industrialisation and the mass production of electronic components on flexible ceramic substrates.